- Design
- Retrospective cohort with linked primary care, hospital and death data
- Population
- 476,620 knee, hip and shoulder arthroplasties in the UK, 2007 to 2019
- Primary outcome
- VTE within 6 months
- Effect
- 1.5% overall (knee 1.6%, hip 1.4%, shoulder 1.0%); >30% found only via linkage
Linked UK primary care, hospital and death records covered 476,620 knee, hip and shoulder arthroplasties from 2007 to 2019. Six-month VTE incidence was 1.5% — 1.6% after knee, 1.4% after hip and 1.0% after shoulder arthroplasty.
More than 30% of VTE events were found only through linkage, meaning hospital data alone would have missed them. Rates fell over time for hips and knees, but the introduction of NICE guidelines in 2010, 2012 and 2018 was not associated with a step change. Shoulder VTE fell 9% after 2018. Risk varied by season differently for each joint.
The practical point is that many VTEs present to the GP, not the surgeon, and outcome audits based on readmission undercount them.
- Tell patients VTE can present weeks after discharge, and what to look for.
- Make sure discharge letters state the prophylaxis plan and duration for the GP.
- Do not judge a unit's VTE rate from readmissions alone.
- Consider shoulder arthroplasty VTE risk explicitly; it is lower but not negligible.
Why it matters
Hospital-based audit misses about a third of post-arthroplasty VTE, which understates the risk surgeons discuss with patients.
Don't overread it
The lack of guideline effect comes from time-series modelling and cannot show that prophylaxis does not work.
The statistics, in plain English
A 1.5% six-month risk is about 1 in 67 patients. Trend tests show direction over time but not cause. The guideline analysis looks for a jump at each date; gradual change already under way can hide one.
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